Datasheet

1124
SAM4S Series [DATASHEET]
11100F–ATARM–29-Jan-14
44.5.3 32.768 kHz Crystal Oscillator Characteristics
Note: 1. R
S
is the series resistor.
C
LEXT
= 2x(C
CRYSTAL
– C
para
– C
PCB
).
Where
C
PCB
is the capacitance of the printed circuit board (PCB) track layout from the crystal to the SAM4 pin.
44.5.4 32.768 kHz Crystal Characteristics
Table 44-26. 32.768 kHz Crystal Oscillator Characteristics
Symbol Parameter Conditions Min Typ Max Unit
f
req
Operating Frequency Normal mode with crystal 32.768 kHz
Duty Cycle 40 50 60 %
Startup Time
Rs < 50 K
Ω
Rs < 100 KΩ
(1)
C
crystal
= 12.5 pF
C
crystal
= 6 pF
C
crystal
= 12.5 pF
C
crystal
= 6 pF
——
900
300
1200
500
ms
I
DD_ON
Current Consumption
Rs < 50 K
Ω
Rs < 100 KΩ
(1)
C
crystal
= 12.5 pF
C
crystal
= 6 pF
C
crystal
= 12.5 pF
C
crystal
= 6 pF
—
550
380
820
530
1150
980
1600
1350
nA
P
ON
Drive Level — — 0.1 µW
R
f
Internal Resistor Between XIN32 and XOUT32 — 10 MΩ
C
LEXT
Maximum External Capacitor
on XIN32 and XOUT32
— — 20 pF
C
para
Internal Parasitic Capacitance 0.6 0.7 0.8 pF
XIN32
XOUT32
C
LEXT
C
LEXT
SAM4
Table 44-27. Crystal Characteristics
Symbol Parameter Conditions Min Typ Max Unit
ESR Equivalent Series Resistor (R
S)
Crystal @ 32.768 kHz — 50 100 KΩ
C
M
Motional Capacitance Crystal @ 32.768 kHz 0.6 — 3 fF
C
SHUNT
Shunt Capacitance Crystal @ 32.768 kHz 0.6 — 2 pF